1. Field of Invention
The present invention is directed to a heat shield for a sliding gate valve. The sliding gate valve has particular application as a furnace valve in which the pouring orifice is substantially horizontal and the plane of the heat shield is substantially vertical.
2. Summary of the Prior Art
The prior art is exemplified by Shapland U.S. Pat. No. 4,063,668 issued December 1977 and also patents of Metacon AG numbered U.S. Pat. Nos. 4,269,399 and 4,273,315.
As to the Shapland U.S. Pat. No. 4,063,668 it should be noted that it utilizes bilaterally symmetrical slide gates and top plates. While the use on a bottom pour vessel such as a ladle, where there is substantial clearance, has been highly satisfactory; when employed on the side of a furnace where extensive auxiliary equipment appears, space limitations can cause a problem.
The Metacon U.S. Pat. Nos. 4,269,399 and 4,273,315 both utilize a slide gate which shuts off in the down position. This has the distinct disadvantage when errosion occurs near the bore of the slide gate or the stationary plate, of providing a pocket for slag or metal to solidify and further, upon reactivation, cause additional errosion.
Furthermore, with the valves which close in the down position, upon opening the metal cascades from an upper position to a lower position on the pour nozzle causing a free-fall area which initially creates a turbulence and additional errosion potential adjacent the portion of the nozzle which slides against the stationary plate. This condition can be agravated when throttling.
Accordingly it becomes desirable to develop a furnace valve which minimizes space, minimizes the potential of a pocket where slag or metal can collect in the off position, and to provide for activating the pouring with a direct connection between the furnace opening and stationary plate and the bottom portion of the pouring nozzle which communicates with either a trough or directly to a ladel.